A boy with a persimmon-dyed crew cut communicated by writing messages on an erasable board until his pen ran dry.

They were among 40 or so students at Alexandria's T.C. Williams High School who did not speak yesterday in observance of the ninth annual "Day of Silence" -- an event that, as notes they passed out explained, was a way of "protesting the silence faced by lesbian, gay, bisexual and transgender people and their allies."

The Day of Silence -- which started at the University of Virginia in 1996 and which also is observed on college campuses -- is sponsored by the New York-based Gay, Lesbian and Straight Education Network, which said it expected 450,000 students at nearly 4,000 high schools, middle schools and colleges to participate this year.

"It represents the silence which gay, lesbian, transgender, bisexual, queer and questioning people face at school because of bullying and harassment," said Morgan Frankena, 17, who is president of the Gay-Straight Alliance at T.C. Williams and an organizer of the event. "It's like they're forced into silence."

A study commissioned last year by the network and conducted by Penn Schoen & Berland Associates Inc. found that 5 percent of high school students nationwide identify themselves as lesbian or gay and that 16 percent say they have a gay or lesbian relative.

Students at Wakefield and Washington-Lee high schools in Arlington and a dozen Montgomery County schools were among those participating. A "Day of Silence" Web site posted a long list of public and private schools in the area that had registered.

At T.C. Williams, where students have participated for the past three years, Frankena arrived a half-hour before the 8:15 a.m. start of classes to sell "Day of Silence" T-shirts designed by a T.C. Williams student. She also distributed messages that students could give to teachers and peers explaining why they were not speaking.

Ralph Dela Rosa, 18, the young man with the persimmon hair, scribbled "G-Luck" on his message board, grinned at his fellow participants and sped off to class.

In a senior government course, Frankena and three other young women sat mutely with yellow sticky-notes on their chests as their classmates talked animatedly about the interstate transportation of alcohol and firearms. One student jokingly tried to make them talk, saying, "Do I look like I could stay silent for one second, let alone one day?" By the end of class, two of the young women had cracked.

But before school, Kathryn Milyko, 18, who was participating for the third year, said that in the past, other students had surprised her with their openness. "I didn't expect them to support me, and they've been really great," she said.

Frankena said T.C. Williams seems to be more tolerant than schools in other states whose Day of Silence organizers she had talked to. But even at T.C. Williams, not everyone supported the event. And Frankena said she saw one student yesterday handing out fliers about health risks associated with gay sex.

Caitlin Thomson, 16, a Wakefield sophomore who last year helped make a film about the school's Day of Silence, said she hoped that people would not feel pressured to join the event or be seen as homophobic if they didn't.